[PATCH v4 16/16] usb/gadget: FunctionFS: add configfs support

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Add support for using FunctionFS in configfs-based USB gadgets.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@xxxxxxxxxxx>
Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
---
 Documentation/ABI/testing/configfs-usb-gadget-ffs |    9 +++
 drivers/usb/gadget/Kconfig                        |   12 +++
 drivers/usb/gadget/f_fs.c                         |   77 +++++++++++++++++++++
 drivers/usb/gadget/u_fs.h                         |    5 ++
 4 files changed, 103 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/ABI/testing/configfs-usb-gadget-ffs

diff --git a/Documentation/ABI/testing/configfs-usb-gadget-ffs b/Documentation/ABI/testing/configfs-usb-gadget-ffs
new file mode 100644
index 0000000..14343e2
--- /dev/null
+++ b/Documentation/ABI/testing/configfs-usb-gadget-ffs
@@ -0,0 +1,9 @@
+What:		/config/usb-gadget/gadget/functions/ffs.name
+Date:		Nov 2013
+KenelVersion:	3.13
+Description:	The purpose of this directory is to create and remove it.
+
+		A corresponding USB function instance is created/removed.
+		There are no attributes here.
+
+		All parameters are set through FunctionFS.
diff --git a/drivers/usb/gadget/Kconfig b/drivers/usb/gadget/Kconfig
index 2479644..8da2b1d 100644
--- a/drivers/usb/gadget/Kconfig
+++ b/drivers/usb/gadget/Kconfig
@@ -689,6 +689,18 @@ config USB_CONFIGFS_MASS_STORAGE
 	  device (in much the same way as the "loop" device driver),
 	  specified as a module parameter or sysfs option.
 
+config USB_CONFIGFS_F_FS
+	boolean "Function filesystem (FunctionFS)"
+	depends on USB_CONFIGFS
+	select USB_F_FS
+	help
+	  The Function Filesystem (FunctionFS) lets one create USB
+	  composite functions in user space in the same way GadgetFS
+	  lets one create USB gadgets in user space.  This allows creation
+	  of composite gadgets such that some of the functions are
+	  implemented in kernel space (for instance Ethernet, serial or
+	  mass storage) and other are implemented in user space.
+
 config USB_ZERO
 	tristate "Gadget Zero (DEVELOPMENT)"
 	select USB_LIBCOMPOSITE
diff --git a/drivers/usb/gadget/f_fs.c b/drivers/usb/gadget/f_fs.c
index e9eaa91..8a81e98 100644
--- a/drivers/usb/gadget/f_fs.c
+++ b/drivers/usb/gadget/f_fs.c
@@ -29,6 +29,7 @@
 #include <linux/usb/functionfs.h>
 
 #include "u_fs.h"
+#include "configfs.h"
 
 #define FUNCTIONFS_MAGIC	0xa647361 /* Chosen by a honest dice roll ;) */
 
@@ -2294,6 +2295,31 @@ static struct ffs_dev *ffs_find_dev(const char *name)
 	return _ffs_find_dev(name);
 }
 
+/* Configfs support *********************************************************/
+
+static inline struct f_fs_opts *to_ffs_opts(struct config_item *item)
+{
+	return container_of(to_config_group(item), struct f_fs_opts,
+			    func_inst.group);
+}
+
+static void ffs_attr_release(struct config_item *item)
+{
+	struct f_fs_opts *opts = to_ffs_opts(item);
+
+	usb_put_function_instance(&opts->func_inst);
+}
+
+static struct configfs_item_operations ffs_item_ops = {
+	.release	= ffs_attr_release,
+};
+
+static struct config_item_type ffs_func_type = {
+	.ct_item_ops	= &ffs_item_ops,
+	.ct_owner	= THIS_MODULE,
+};
+
+
 /* Function registration interface ******************************************/
 
 static void ffs_free_inst(struct usb_function_instance *f)
@@ -2307,6 +2333,44 @@ static void ffs_free_inst(struct usb_function_instance *f)
 	kfree(opts);
 }
 
+#define MAX_INST_NAME_LEN	40
+
+static int ffs_set_inst_name(struct usb_function_instance *fi, const char *name)
+{
+	struct f_fs_opts *opts;
+	char *ptr;
+	const char *tmp;
+	int name_len, ret;
+
+	name_len = strlen(name) + 1;
+	if (name_len > MAX_INST_NAME_LEN)
+		return -ENAMETOOLONG;
+
+	ptr = kstrndup(name, name_len, GFP_KERNEL);
+	if (!ptr)
+		return -ENOMEM;
+
+	opts = to_f_fs_opts(fi);
+	tmp = NULL;
+
+	ffs_dev_lock();
+
+	tmp = opts->dev->name_allocated ? opts->dev->name : NULL;
+	ret = ffs_name_dev(opts->dev, ptr);
+	if (ret) {
+		kfree(ptr);
+		ffs_dev_unlock();
+		return ret;
+	}
+	opts->dev->name_allocated = true;
+	
+	ffs_dev_unlock();
+
+	kfree(tmp);
+
+	return 0;
+}
+
 static struct usb_function_instance *ffs_alloc_inst(void)
 {
 	struct f_fs_opts *opts;
@@ -2316,6 +2380,7 @@ static struct usb_function_instance *ffs_alloc_inst(void)
 	if (!opts)
 		return ERR_PTR(-ENOMEM);
 
+	opts->func_inst.set_inst_name = ffs_set_inst_name;
 	opts->func_inst.free_func_inst = ffs_free_inst;
 	ffs_dev_lock();
 	dev = ffs_alloc_dev();
@@ -2325,7 +2390,10 @@ static struct usb_function_instance *ffs_alloc_inst(void)
 		return ERR_CAST(dev);
 	}
 	opts->dev = dev;
+	dev->opts = opts;
 
+	config_group_init_type_name(&opts->func_inst.group, "",
+				    &ffs_func_type);
 	return &opts->func_inst;
 }
 
@@ -2466,6 +2534,8 @@ EXPORT_SYMBOL(ffs_single_dev);
 void ffs_free_dev(struct ffs_dev *dev)
 {
 	list_del(&dev->entry);
+	if (dev->name_allocated)
+		kfree(dev->name);
 	kfree(dev);
 	if (list_empty(&ffs_devices))
 		functionfs_cleanup();
@@ -2554,6 +2624,13 @@ static void ffs_closed(struct ffs_data *ffs)
 
 	if (ffs_obj->ffs_closed_callback)
 		ffs_obj->ffs_closed_callback(ffs);
+
+	if (!ffs_obj->opts || ffs_obj->opts->no_configfs
+	    || !ffs_obj->opts->func_inst.group.cg_item.ci_parent)
+		goto done;
+	
+	unregister_gadget_item(ffs_obj->opts->
+			       func_inst.group.cg_item.ci_parent->ci_parent);
 done:
 	ffs_dev_unlock();
 }
diff --git a/drivers/usb/gadget/u_fs.h b/drivers/usb/gadget/u_fs.h
index 9ea4215..70e3527 100644
--- a/drivers/usb/gadget/u_fs.h
+++ b/drivers/usb/gadget/u_fs.h
@@ -20,6 +20,8 @@
 #include <linux/list.h>
 #include <linux/mutex.h>
 
+#define VERBOSE_DEBUG
+
 #ifdef VERBOSE_DEBUG
 #ifndef pr_vdebug
 #  define pr_vdebug pr_debug
@@ -35,13 +37,16 @@
 
 #define ENTER()    pr_vdebug("%s()\n", __func__)
 
+struct f_fs_opts;
 
 struct ffs_dev {
 	const char *name;
+	bool name_allocated;
 	bool mounted;
 	bool desc_ready;
 	bool single;
 	struct ffs_data *ffs_data;
+	struct f_fs_opts *opts;
 	struct list_head entry;
 
 	int (*ffs_ready_callback)(struct ffs_data *ffs);
-- 
1.7.0.4

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